package com.shiguiwu.springboot3.gateway.exception;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.web.reactive.error.ErrorWebExceptionHandler;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.annotation.Order;
import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.http.MediaType;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.web.server.ResponseStatusException;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

@Slf4j
@Order(-1)
@RequiredArgsConstructor
@Configuration
public class GlobalExceptionConfiguration implements ErrorWebExceptionHandler {
    private final ObjectMapper objectMapper;

    @Override 
    public Mono<Void> handle(ServerWebExchange exchange, Throwable ex) {
        ServerHttpResponse response = exchange.getResponse();

        if (response.isCommitted()) { 
            return Mono.error(ex); 
        } 

        // header set 
        response.getHeaders().setContentType(MediaType.APPLICATION_JSON);

        if (ex instanceof ResponseStatusException) {
            response.setStatusCode(((ResponseStatusException) ex).getStatusCode());
        }


        log.error("[网关异常处理]请求路径:{},异常信息:{}", exchange.getRequest().getPath(), ex.getMessage());
        return response.writeWith(Mono.fromSupplier(() -> { 
            DataBufferFactory bufferFactory = response.bufferFactory();
            try { 
                return bufferFactory.wrap(objectMapper.writeValueAsBytes(ex.getMessage()));
            } catch (JsonProcessingException e) {
                log.warn("Error writing response", ex); 
                return bufferFactory.wrap(new byte[0]); 
            } 
        })); 
    } 
}
